In recent years, a search technique in Internet is enhanced, and not only sentences but also images or animations are searched. For example, Patent Document 1 discloses therein an information search device capable of determining a search range based on metadata associated with information (file) such as images and specifying a granularity of the search range based on a unit of numerical information contained in a query when searching a file from a database. More specifically, for a query for specifying the search range, a first number and a keyword are input to specify an annual or monthly granularity of the first number, thereby obtaining a second number of a granularity corresponding to the keyword, and a file contained in the search range determined by the first and second numbers is searched from a plurality of files.